As a method for producing a polymerized toner, for example, there is proposed a suspension polymerization method wherein a polymerizable composition is dispersed in an aqueous medium and then polymerized, as described in Japanese Patent Kokai 1-201676. This suspension polymerization method requires no pulverization, and a colorant and an additive are uniformly dispersed in comparison with a conventional method.
However, a polymerized toner obtained by this method normally has a large particle size (5 to 15.mu.) and has large particle size distribution. Therefore, a classifying step is required. When a toner having small particle size (3 to 7.mu.) which has recently been required is produced, yield is lowered.
As a method for producing a toner having a small particle size, for example, there is proposed a method based on a non-aqueous dispersion polymerization which comprises polymerizing vinyl monomers in the presence of a colorant in a dispersion solvent to which the vinyl monomers are soluble and polymerized particles therefrom are insoluble, as described in Japanese Patent Kokai Nos. 61-273552 and 62-73276.
However, in this method, there is not disclosed an improvement for finely dispersing a colorant and an additive to polymerize them and, therefore, it is remarkably difficult to allow a release agent which prevents a toner from adhering to a fixing roll to be uniformly present in polymerized particles. The release agent has no affinity with a dispersion solvent and, therefore, the release agent agglomerates in a polymerization system and deposits apart from polymerized particles, whereby, it is not practicable to contain the release agent in polymerized particles.
In Japanese Patent Kokai No. 1-137264, there is disclosed a technique for encapsulating a release agent and a polymer in toner particles, however, all possible production processes are listed and a suitable one is not specified. The polymer component described therein is not uniformly dissolved or dispersed in a dispersion solvent. Therefore, it is difficult to uniformly contain the release agent in polymerized particles, whereby, the resulting toner has large particle size distribution and comparatively large particle size.